Polymerizable monomers

Abstract

A monomer of formula (1) is provided wherein R 1 is hydrogen or a monovalent C 1 -C 6 hydrocarbon group, and R 2 is a group having polymerization functionality. Using the monomer, crosslinking units can be incorporated into a polymer chain. A chemically amplified negative resist composition comprising a base polymer having crosslinking units incorporated therein has a high sensitivity and forms a resist pattern with minimized LER.

The invention claimed is: 
     
       1. A monomer of formula (1): 
       
         
           
           
               
               
           
         
         wherein R l  is hydrogen or a monovalent, straight, branched or cyclic hydrocarbon group of 1 to 6 carbon atoms, and R 2  is a monovalent group having polymerization functionality. 
       
     
     
       2. The monomer of  claim 1  wherein R 2  is a group of formula (2) or (3): 
       
         
           
           
               
               
           
         
         wherein R 3  is hydrogen, fluorine, methyl or trifluoromethyl, and the broken line denotes a valence bond to the oxygen atom, 
       
       
         
           
           
               
               
           
         
         wherein R 4  is hydrogen or methyl, R 5  is each independently a monovalent, straight, branched or cyclic hydrocarbon group of 1 to 6 carbon atoms which may contain oxygen, or halogen, n is an integer of 0 to 2, m is an integer of 0 to (4+2n), and the broken line denotes a valence bond to the oxygen atom.